arch/x86/tools/relocs.c

   1 #include <stdio.h>
   2 #include <stdarg.h>
   3 #include <stdlib.h>
   4 #include <stdint.h>
   5 #include <string.h>
   6 #include <errno.h>
   7 #include <unistd.h>
   8 #include <elf.h>
   9 #include <byteswap.h>
  10 #define USE_BSD
  11 #include <endian.h>
  12 #include <regex.h>
  13
  14 static void die(char *fmt, ...);
  15
  16 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
  17 static Elf32_Ehdr ehdr;
  18 static unsigned long reloc_count, reloc_idx;
  19 static unsigned long *relocs;
  20 static unsigned long reloc16_count, reloc16_idx;
  21 static unsigned long *relocs16;
  22
  23 struct section {
  24         Elf32_Shdr     shdr;
  25         struct section *link;
  26         Elf32_Sym      *symtab;
  27         Elf32_Rel      *reltab;
  28         char           *strtab;
  29 };
  30 static struct section *secs;
  31
  32 enum symtype {
  33         S_ABS,
  34         S_REL,
  35         S_SEG,
  36         S_LIN,
  37         S_NSYMTYPES
  38 };
  39
  40 static const char * const sym_regex_kernel[S_NSYMTYPES] = {
  41 /*
  42  * Following symbols have been audited. There values are constant and do
  43  * not change if bzImage is loaded at a different physical address than
  44  * the address for which it has been compiled. Don't warn user about
  45  * absolute relocations present w.r.t these symbols.
  46  */
  47         [S_ABS] =
  48         "^(xen_irq_disable_direct_reloc$|"
  49         "xen_save_fl_direct_reloc$|"
  50         "VDSO|"
  51         "__crc_)",
  52
  53 /*
  54  * These symbols are known to be relative, even if the linker marks them
  55  * as absolute (typically defined outside any section in the linker script.)
  56  */
  57         [S_REL] =
  58         "^(__init_(begin|end)|"
  59         "__x86_cpu_dev_(start|end)|"
  60         "(__parainstructions|__alt_instructions)(|_end)|"
  61         "(__iommu_table|__apicdrivers|__smp_locks)(|_end)|"
  62         "__(start|end)_pci_.*|"
  63         "__(start|end)_builtin_fw|"
  64         "__(start|stop)___ksymtab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
  65         "__(start|stop)___kcrctab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
  66         "__(start|stop)___param|"
  67         "__(start|stop)___modver|"
  68         "__(start|stop)___bug_table|"
  69         "__tracedata_(start|end)|"
  70         "__(start|stop)_notes|"
  71         "__end_rodata|"
  72         "__initramfs_start|"
  73         "_end)$"
  74 };
  75
  76
  77 static const char * const sym_regex_realmode[S_NSYMTYPES] = {
  78 /*
  79  * These are 16-bit segment symbols when compiling 16-bit code.
  80  */
  81         [S_SEG] =
  82         "^real_mode_seg$",
  83
  84 /*
  85  * These are offsets belonging to segments, as opposed to linear addresses,
  86  * when compiling 16-bit code.
  87  */
  88         [S_LIN] =
  89         "^pa_",
  90 };
  91
  92 static const char * const *sym_regex;
  93
  94 static regex_t sym_regex_c[S_NSYMTYPES];
  95 static int is_reloc(enum symtype type, const char *sym_name)
  96 {
  97         return sym_regex[type] &&
  98                 !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
  99 }
 100
 101 static void regex_init(int use_real_mode)
 102 {
 103         char errbuf[128];
 104         int err;
 105         int i;
 106
 107         if (use_real_mode)
 108                 sym_regex = sym_regex_realmode;
 109         else
 110                 sym_regex = sym_regex_kernel;
 111
 112         for (i = 0; i < S_NSYMTYPES; i++) {
 113                 if (!sym_regex[i])
 114                         continue;
 115
 116                 err = regcomp(&sym_regex_c[i], sym_regex[i],
 117                               REG_EXTENDED|REG_NOSUB);
 118
 119                 if (err) {
 120                         regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf);
 121                         die("%s", errbuf);
 122                 }
 123         }
 124 }
 125
 126 static void die(char *fmt, ...)
 127 {
 128         va_list ap;
 129         va_start(ap, fmt);
 130         vfprintf(stderr, fmt, ap);
 131         va_end(ap);
 132         exit(1);
 133 }
 134
 135 static const char *sym_type(unsigned type)
 136 {
 137         static const char *type_name[] = {
 138 #define SYM_TYPE(X) [X] = #X
 139                 SYM_TYPE(STT_NOTYPE),
 140                 SYM_TYPE(STT_OBJECT),
 141                 SYM_TYPE(STT_FUNC),
 142                 SYM_TYPE(STT_SECTION),
 143                 SYM_TYPE(STT_FILE),
 144                 SYM_TYPE(STT_COMMON),
 145                 SYM_TYPE(STT_TLS),
 146 #undef SYM_TYPE
 147         };
 148         const char *name = "unknown sym type name";
 149         if (type < ARRAY_SIZE(type_name)) {
 150                 name = type_name[type];
 151         }
 152         return name;
 153 }
 154
 155 static const char *sym_bind(unsigned bind)
 156 {
 157         static const char *bind_name[] = {
 158 #define SYM_BIND(X) [X] = #X
 159                 SYM_BIND(STB_LOCAL),
 160                 SYM_BIND(STB_GLOBAL),
 161                 SYM_BIND(STB_WEAK),
 162 #undef SYM_BIND
 163         };
 164         const char *name = "unknown sym bind name";
 165         if (bind < ARRAY_SIZE(bind_name)) {
 166                 name = bind_name[bind];
 167         }
 168         return name;
 169 }
 170
 171 static const char *sym_visibility(unsigned visibility)
 172 {
 173         static const char *visibility_name[] = {
 174 #define SYM_VISIBILITY(X) [X] = #X
 175                 SYM_VISIBILITY(STV_DEFAULT),
 176                 SYM_VISIBILITY(STV_INTERNAL),
 177                 SYM_VISIBILITY(STV_HIDDEN),
 178                 SYM_VISIBILITY(STV_PROTECTED),
 179 #undef SYM_VISIBILITY
 180         };
 181         const char *name = "unknown sym visibility name";
 182         if (visibility < ARRAY_SIZE(visibility_name)) {
 183                 name = visibility_name[visibility];
 184         }
 185         return name;
 186 }
 187
 188 static const char *rel_type(unsigned type)
 189 {
 190         static const char *type_name[] = {
 191 #define REL_TYPE(X) [X] = #X
 192                 REL_TYPE(R_386_NONE),
 193                 REL_TYPE(R_386_32),
 194                 REL_TYPE(R_386_PC32),
 195                 REL_TYPE(R_386_GOT32),
 196                 REL_TYPE(R_386_PLT32),
 197                 REL_TYPE(R_386_COPY),
 198                 REL_TYPE(R_386_GLOB_DAT),
 199                 REL_TYPE(R_386_JMP_SLOT),
 200                 REL_TYPE(R_386_RELATIVE),
 201                 REL_TYPE(R_386_GOTOFF),
 202                 REL_TYPE(R_386_GOTPC),
 203                 REL_TYPE(R_386_8),
 204                 REL_TYPE(R_386_PC8),
 205                 REL_TYPE(R_386_16),
 206                 REL_TYPE(R_386_PC16),
 207 #undef REL_TYPE
 208         };
 209         const char *name = "unknown type rel type name";
 210         if (type < ARRAY_SIZE(type_name) && type_name[type]) {
 211                 name = type_name[type];
 212         }
 213         return name;
 214 }
 215
 216 static const char *sec_name(unsigned shndx)
 217 {
 218         const char *sec_strtab;
 219         const char *name;
 220         sec_strtab = secs[ehdr.e_shstrndx].strtab;
 221         name = "<noname>";
 222         if (shndx < ehdr.e_shnum) {
 223                 name = sec_strtab + secs[shndx].shdr.sh_name;
 224         }
 225         else if (shndx == SHN_ABS) {
 226                 name = "ABSOLUTE";
 227         }
 228         else if (shndx == SHN_COMMON) {
 229                 name = "COMMON";
 230         }
 231         return name;
 232 }
 233
 234 static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
 235 {
 236         const char *name;
 237         name = "<noname>";
 238         if (sym->st_name) {
 239                 name = sym_strtab + sym->st_name;
 240         }
 241         else {
 242                 name = sec_name(sym->st_shndx);
 243         }
 244         return name;
 245 }
 246
 247
 248
 249 #if BYTE_ORDER == LITTLE_ENDIAN
 250 #define le16_to_cpu(val) (val)
 251 #define le32_to_cpu(val) (val)
 252 #endif
 253 #if BYTE_ORDER == BIG_ENDIAN
 254 #define le16_to_cpu(val) bswap_16(val)
 255 #define le32_to_cpu(val) bswap_32(val)
 256 #endif
 257
 258 static uint16_t elf16_to_cpu(uint16_t val)
 259 {
 260         return le16_to_cpu(val);
 261 }
 262
 263 static uint32_t elf32_to_cpu(uint32_t val)
 264 {
 265         return le32_to_cpu(val);
 266 }
 267
 268 static void read_ehdr(FILE *fp)
 269 {
 270         if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
 271                 die("Cannot read ELF header: %s\n",
 272                         strerror(errno));
 273         }
 274         if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
 275                 die("No ELF magic\n");
 276         }
 277         if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) {
 278                 die("Not a 32 bit executable\n");
 279         }
 280         if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
 281                 die("Not a LSB ELF executable\n");
 282         }
 283         if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
 284                 die("Unknown ELF version\n");
 285         }
 286         /* Convert the fields to native endian */
 287         ehdr.e_type      = elf16_to_cpu(ehdr.e_type);
 288         ehdr.e_machine   = elf16_to_cpu(ehdr.e_machine);
 289         ehdr.e_version   = elf32_to_cpu(ehdr.e_version);
 290         ehdr.e_entry     = elf32_to_cpu(ehdr.e_entry);
 291         ehdr.e_phoff     = elf32_to_cpu(ehdr.e_phoff);
 292         ehdr.e_shoff     = elf32_to_cpu(ehdr.e_shoff);
 293         ehdr.e_flags     = elf32_to_cpu(ehdr.e_flags);
 294         ehdr.e_ehsize    = elf16_to_cpu(ehdr.e_ehsize);
 295         ehdr.e_phentsize = elf16_to_cpu(ehdr.e_phentsize);
 296         ehdr.e_phnum     = elf16_to_cpu(ehdr.e_phnum);
 297         ehdr.e_shentsize = elf16_to_cpu(ehdr.e_shentsize);
 298         ehdr.e_shnum     = elf16_to_cpu(ehdr.e_shnum);
 299         ehdr.e_shstrndx  = elf16_to_cpu(ehdr.e_shstrndx);
 300
 301         if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
 302                 die("Unsupported ELF header type\n");
 303         }
 304         if (ehdr.e_machine != EM_386) {
 305                 die("Not for x86\n");
 306         }
 307         if (ehdr.e_version != EV_CURRENT) {
 308                 die("Unknown ELF version\n");
 309         }
 310         if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) {
 311                 die("Bad Elf header size\n");
 312         }
 313         if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) {
 314                 die("Bad program header entry\n");
 315         }
 316         if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
 317                 die("Bad section header entry\n");
 318         }
 319         if (ehdr.e_shstrndx >= ehdr.e_shnum) {
 320                 die("String table index out of bounds\n");
 321         }
 322 }
 323
 324 static void read_shdrs(FILE *fp)
 325 {
 326         int i;
 327         Elf32_Shdr shdr;
 328
 329         secs = calloc(ehdr.e_shnum, sizeof(struct section));
 330         if (!secs) {
 331                 die("Unable to allocate %d section headers\n",
 332                     ehdr.e_shnum);
 333         }
 334         if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
 335                 die("Seek to %d failed: %s\n",
 336                         ehdr.e_shoff, strerror(errno));
 337         }
 338         for (i = 0; i < ehdr.e_shnum; i++) {
 339                 struct section *sec = &secs[i];
 340                 if (fread(&shdr, sizeof shdr, 1, fp) != 1)
 341                         die("Cannot read ELF section headers %d/%d: %s\n",
 342                             i, ehdr.e_shnum, strerror(errno));
 343                 sec->shdr.sh_name      = elf32_to_cpu(shdr.sh_name);
 344                 sec->shdr.sh_type      = elf32_to_cpu(shdr.sh_type);
 345                 sec->shdr.sh_flags     = elf32_to_cpu(shdr.sh_flags);
 346                 sec->shdr.sh_addr      = elf32_to_cpu(shdr.sh_addr);
 347                 sec->shdr.sh_offset    = elf32_to_cpu(shdr.sh_offset);
 348                 sec->shdr.sh_size      = elf32_to_cpu(shdr.sh_size);
 349                 sec->shdr.sh_link      = elf32_to_cpu(shdr.sh_link);
 350                 sec->shdr.sh_info      = elf32_to_cpu(shdr.sh_info);
 351                 sec->shdr.sh_addralign = elf32_to_cpu(shdr.sh_addralign);
 352                 sec->shdr.sh_entsize   = elf32_to_cpu(shdr.sh_entsize);
 353                 if (sec->shdr.sh_link < ehdr.e_shnum)
 354                         sec->link = &secs[sec->shdr.sh_link];
 355         }
 356
 357 }
 358
 359 static void read_strtabs(FILE *fp)
 360 {
 361         int i;
 362         for (i = 0; i < ehdr.e_shnum; i++) {
 363                 struct section *sec = &secs[i];
 364                 if (sec->shdr.sh_type != SHT_STRTAB) {
 365                         continue;
 366                 }
 367                 sec->strtab = malloc(sec->shdr.sh_size);
 368                 if (!sec->strtab) {
 369                         die("malloc of %d bytes for strtab failed\n",
 370                                 sec->shdr.sh_size);
 371                 }
 372                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 373                         die("Seek to %d failed: %s\n",
 374                                 sec->shdr.sh_offset, strerror(errno));
 375                 }
 376                 if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
 377                     != sec->shdr.sh_size) {
 378                         die("Cannot read symbol table: %s\n",
 379                                 strerror(errno));
 380                 }
 381         }
 382 }
 383
 384 static void read_symtabs(FILE *fp)
 385 {
 386         int i,j;
 387         for (i = 0; i < ehdr.e_shnum; i++) {
 388                 struct section *sec = &secs[i];
 389                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 390                         continue;
 391                 }
 392                 sec->symtab = malloc(sec->shdr.sh_size);
 393                 if (!sec->symtab) {
 394                         die("malloc of %d bytes for symtab failed\n",
 395                                 sec->shdr.sh_size);
 396                 }
 397                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 398                         die("Seek to %d failed: %s\n",
 399                                 sec->shdr.sh_offset, strerror(errno));
 400                 }
 401                 if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
 402                     != sec->shdr.sh_size) {
 403                         die("Cannot read symbol table: %s\n",
 404                                 strerror(errno));
 405                 }
 406                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) {
 407                         Elf32_Sym *sym = &sec->symtab[j];
 408                         sym->st_name  = elf32_to_cpu(sym->st_name);
 409                         sym->st_value = elf32_to_cpu(sym->st_value);
 410                         sym->st_size  = elf32_to_cpu(sym->st_size);
 411                         sym->st_shndx = elf16_to_cpu(sym->st_shndx);
 412                 }
 413         }
 414 }
 415
 416
 417 static void read_relocs(FILE *fp)
 418 {
 419         int i,j;
 420         for (i = 0; i < ehdr.e_shnum; i++) {
 421                 struct section *sec = &secs[i];
 422                 if (sec->shdr.sh_type != SHT_REL) {
 423                         continue;
 424                 }
 425                 sec->reltab = malloc(sec->shdr.sh_size);
 426                 if (!sec->reltab) {
 427                         die("malloc of %d bytes for relocs failed\n",
 428                                 sec->shdr.sh_size);
 429                 }
 430                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 431                         die("Seek to %d failed: %s\n",
 432                                 sec->shdr.sh_offset, strerror(errno));
 433                 }
 434                 if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
 435                     != sec->shdr.sh_size) {
 436                         die("Cannot read symbol table: %s\n",
 437                                 strerror(errno));
 438                 }
 439                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
 440                         Elf32_Rel *rel = &sec->reltab[j];
 441                         rel->r_offset = elf32_to_cpu(rel->r_offset);
 442                         rel->r_info   = elf32_to_cpu(rel->r_info);
 443                 }
 444         }
 445 }
 446
 447
 448 static void print_absolute_symbols(void)
 449 {
 450         int i;
 451         printf("Absolute symbols\n");
 452         printf(" Num:    Value Size  Type       Bind        Visibility  Name\n");
 453         for (i = 0; i < ehdr.e_shnum; i++) {
 454                 struct section *sec = &secs[i];
 455                 char *sym_strtab;
 456                 int j;
 457
 458                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 459                         continue;
 460                 }
 461                 sym_strtab = sec->link->strtab;
 462                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) {
 463                         Elf32_Sym *sym;
 464                         const char *name;
 465                         sym = &sec->symtab[j];
 466                         name = sym_name(sym_strtab, sym);
 467                         if (sym->st_shndx != SHN_ABS) {
 468                                 continue;
 469                         }
 470                         printf("%5d %08x %5d %10s %10s %12s %s\n",
 471                                 j, sym->st_value, sym->st_size,
 472                                 sym_type(ELF32_ST_TYPE(sym->st_info)),
 473                                 sym_bind(ELF32_ST_BIND(sym->st_info)),
 474                                 sym_visibility(ELF32_ST_VISIBILITY(sym->st_other)),
 475                                 name);
 476                 }
 477         }
 478         printf("\n");
 479 }
 480
 481 static void print_absolute_relocs(void)
 482 {
 483         int i, printed = 0;
 484
 485         for (i = 0; i < ehdr.e_shnum; i++) {
 486                 struct section *sec = &secs[i];
 487                 struct section *sec_applies, *sec_symtab;
 488                 char *sym_strtab;
 489                 Elf32_Sym *sh_symtab;
 490                 int j;
 491                 if (sec->shdr.sh_type != SHT_REL) {
 492                         continue;
 493                 }
 494                 sec_symtab  = sec->link;
 495                 sec_applies = &secs[sec->shdr.sh_info];
 496                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 497                         continue;
 498                 }
 499                 sh_symtab  = sec_symtab->symtab;
 500                 sym_strtab = sec_symtab->link->strtab;
 501                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
 502                         Elf32_Rel *rel;
 503                         Elf32_Sym *sym;
 504                         const char *name;
 505                         rel = &sec->reltab[j];
 506                         sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
 507                         name = sym_name(sym_strtab, sym);
 508                         if (sym->st_shndx != SHN_ABS) {
 509                                 continue;
 510                         }
 511
 512                         /* Absolute symbols are not relocated if bzImage is
 513                          * loaded at a non-compiled address. Display a warning
 514                          * to user at compile time about the absolute
 515                          * relocations present.
 516                          *
 517                          * User need to audit the code to make sure
 518                          * some symbols which should have been section
 519                          * relative have not become absolute because of some
 520                          * linker optimization or wrong programming usage.
 521                          *
 522                          * Before warning check if this absolute symbol
 523                          * relocation is harmless.
 524                          */
 525                         if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
 526                                 continue;
 527
 528                         if (!printed) {
 529                                 printf("WARNING: Absolute relocations"
 530                                         " present\n");
 531                                 printf("Offset     Info     Type     Sym.Value "
 532                                         "Sym.Name\n");
 533                                 printed = 1;
 534                         }
 535
 536                         printf("%08x %08x %10s %08x  %s\n",
 537                                 rel->r_offset,
 538                                 rel->r_info,
 539                                 rel_type(ELF32_R_TYPE(rel->r_info)),
 540                                 sym->st_value,
 541                                 name);
 542                 }
 543         }
 544
 545         if (printed)
 546                 printf("\n");
 547 }
 548
 549 static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym),
 550                         int use_real_mode)
 551 {
 552         int i;
 553         /* Walk through the relocations */
 554         for (i = 0; i < ehdr.e_shnum; i++) {
 555                 char *sym_strtab;
 556                 Elf32_Sym *sh_symtab;
 557                 struct section *sec_applies, *sec_symtab;
 558                 int j;
 559                 struct section *sec = &secs[i];
 560
 561                 if (sec->shdr.sh_type != SHT_REL) {
 562                         continue;
 563                 }
 564                 sec_symtab  = sec->link;
 565                 sec_applies = &secs[sec->shdr.sh_info];
 566                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 567                         continue;
 568                 }
 569                 sh_symtab = sec_symtab->symtab;
 570                 sym_strtab = sec_symtab->link->strtab;
 571                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
 572                         Elf32_Rel *rel;
 573                         Elf32_Sym *sym;
 574                         unsigned r_type;
 575                         const char *symname;
 576                         int shn_abs;
 577
 578                         rel = &sec->reltab[j];
 579                         sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
 580                         r_type = ELF32_R_TYPE(rel->r_info);
 581
 582                         shn_abs = sym->st_shndx == SHN_ABS;
 583
 584                         switch (r_type) {
 585                         case R_386_NONE:
 586                         case R_386_PC32:
 587                         case R_386_PC16:
 588                         case R_386_PC8:
 589                                 /*
 590                                  * NONE can be ignored and and PC relative
 591                                  * relocations don't need to be adjusted.
 592                                  */
 593                                 break;
 594
 595                         case R_386_16:
 596                                 symname = sym_name(sym_strtab, sym);
 597                                 if (!use_real_mode)
 598                                         goto bad;
 599                                 if (shn_abs) {
 600                                         if (is_reloc(S_ABS, symname))
 601                                                 break;
 602                                         else if (!is_reloc(S_SEG, symname))
 603                                                 goto bad;
 604                                 } else {
 605                                         if (is_reloc(S_LIN, symname))
 606                                                 goto bad;
 607                                         else
 608                                                 break;
 609                                 }
 610                                 visit(rel, sym);
 611                                 break;
 612
 613                         case R_386_32:
 614                                 symname = sym_name(sym_strtab, sym);
 615                                 if (shn_abs) {
 616                                         if (is_reloc(S_ABS, symname))
 617                                                 break;
 618                                         else if (!is_reloc(S_REL, symname))
 619                                                 goto bad;
 620                                 } else {
 621                                         if (use_real_mode &&
 622                                             !is_reloc(S_LIN, symname))
 623                                                 break;
 624                                 }
 625                                 visit(rel, sym);
 626                                 break;
 627                         default:
 628                                 die("Unsupported relocation type: %s (%d)\n",
 629                                     rel_type(r_type), r_type);
 630                                 break;
 631                         bad:
 632                                 symname = sym_name(sym_strtab, sym);
 633                                 die("Invalid %s %s relocation: %s\n",
 634                                     shn_abs ? "absolute" : "relative",
 635                                     rel_type(r_type), symname);
 636                         }
 637                 }
 638         }
 639 }
 640
 641 static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
 642 {
 643         if (ELF32_R_TYPE(rel->r_info) == R_386_16)
 644                 reloc16_count++;
 645         else
 646                 reloc_count++;
 647 }
 648
 649 static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
 650 {
 651         /* Remember the address that needs to be adjusted. */
 652         if (ELF32_R_TYPE(rel->r_info) == R_386_16)
 653                 relocs16[reloc16_idx++] = rel->r_offset;
 654         else
 655                 relocs[reloc_idx++] = rel->r_offset;
 656 }
 657
 658 static int cmp_relocs(const void *va, const void *vb)
 659 {
 660         const unsigned long *a, *b;
 661         a = va; b = vb;
 662         return (*a == *b)? 0 : (*a > *b)? 1 : -1;
 663 }
 664
 665 static int write32(unsigned int v, FILE *f)
 666 {
 667         unsigned char buf[4];
 668
 669         buf[0] = (v >>  0) & 0xff;
 670         buf[1] = (v >>  8) & 0xff;
 671         buf[2] = (v >> 16) & 0xff;
 672         buf[3] = (v >> 24) & 0xff;
 673         return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
 674 }
 675
 676 static void emit_relocs(int as_text, int use_real_mode)
 677 {
 678         int i;
 679         /* Count how many relocations I have and allocate space for them. */
 680         reloc_count = 0;
 681         walk_relocs(count_reloc, use_real_mode);
 682         relocs = malloc(reloc_count * sizeof(relocs[0]));
 683         if (!relocs) {
 684                 die("malloc of %d entries for relocs failed\n",
 685                         reloc_count);
 686         }
 687
 688         relocs16 = malloc(reloc16_count * sizeof(relocs[0]));
 689         if (!relocs16) {
 690                 die("malloc of %d entries for relocs16 failed\n",
 691                         reloc16_count);
 692         }
 693         /* Collect up the relocations */
 694         reloc_idx = 0;
 695         walk_relocs(collect_reloc, use_real_mode);
 696
 697         if (reloc16_count && !use_real_mode)
 698                 die("Segment relocations found but --realmode not specified\n");
 699
 700         /* Order the relocations for more efficient processing */
 701         qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
 702         qsort(relocs16, reloc16_count, sizeof(relocs16[0]), cmp_relocs);
 703
 704         /* Print the relocations */
 705         if (as_text) {
 706                 /* Print the relocations in a form suitable that
 707                  * gas will like.
 708                  */
 709                 printf(".section \".data.reloc\",\"a\"\n");
 710                 printf(".balign 4\n");
 711                 if (use_real_mode) {
 712                         printf("\t.long %lu\n", reloc16_count);
 713                         for (i = 0; i < reloc16_count; i++)
 714                                 printf("\t.long 0x%08lx\n", relocs16[i]);
 715                         printf("\t.long %lu\n", reloc_count);
 716                         for (i = 0; i < reloc_count; i++) {
 717                                 printf("\t.long 0x%08lx\n", relocs[i]);
 718                         }
 719                 } else {
 720                         /* Print a stop */
 721                         printf("\t.long 0x%08lx\n", (unsigned long)0);
 722                         for (i = 0; i < reloc_count; i++) {
 723                                 printf("\t.long 0x%08lx\n", relocs[i]);
 724                         }
 725                 }
 726
 727                 printf("\n");
 728         }
 729         else {
 730                 if (use_real_mode) {
 731                         write32(reloc16_count, stdout);
 732                         for (i = 0; i < reloc16_count; i++)
 733                                 write32(relocs16[i], stdout);
 734                         write32(reloc_count, stdout);
 735
 736                         /* Now print each relocation */
 737                         for (i = 0; i < reloc_count; i++)
 738                                 write32(relocs[i], stdout);
 739                 } else {
 740                         /* Print a stop */
 741                         write32(0, stdout);
 742
 743                         /* Now print each relocation */
 744                         for (i = 0; i < reloc_count; i++) {
 745                                 write32(relocs[i], stdout);
 746                         }
 747                 }
 748         }
 749 }
 750
 751 static void usage(void)
 752 {
 753         die("relocs [--abs-syms|--abs-relocs|--text|--realmode] vmlinux\n");
 754 }
 755
 756 int main(int argc, char **argv)
 757 {
 758         int show_absolute_syms, show_absolute_relocs;
 759         int as_text, use_real_mode;
 760         const char *fname;
 761         FILE *fp;
 762         int i;
 763
 764         show_absolute_syms = 0;
 765         show_absolute_relocs = 0;
 766         as_text = 0;
 767         use_real_mode = 0;
 768         fname = NULL;
 769         for (i = 1; i < argc; i++) {
 770                 char *arg = argv[i];
 771                 if (*arg == '-') {
 772                         if (strcmp(arg, "--abs-syms") == 0) {
 773                                 show_absolute_syms = 1;
 774                                 continue;
 775                         }
 776                         if (strcmp(arg, "--abs-relocs") == 0) {
 777                                 show_absolute_relocs = 1;
 778                                 continue;
 779                         }
 780                         if (strcmp(arg, "--text") == 0) {
 781                                 as_text = 1;
 782                                 continue;
 783                         }
 784                         if (strcmp(arg, "--realmode") == 0) {
 785                                 use_real_mode = 1;
 786                                 continue;
 787                         }
 788                 }
 789                 else if (!fname) {
 790                         fname = arg;
 791                         continue;
 792                 }
 793                 usage();
 794         }
 795         if (!fname) {
 796                 usage();
 797         }
 798         regex_init(use_real_mode);
 799         fp = fopen(fname, "r");
 800         if (!fp) {
 801                 die("Cannot open %s: %s\n",
 802                         fname, strerror(errno));
 803         }
 804         read_ehdr(fp);
 805         read_shdrs(fp);
 806         read_strtabs(fp);
 807         read_symtabs(fp);
 808         read_relocs(fp);
 809         if (show_absolute_syms) {
 810                 print_absolute_symbols();
 811                 return 0;
 812         }
 813         if (show_absolute_relocs) {
 814                 print_absolute_relocs();
 815                 return 0;
 816         }
 817         emit_relocs(as_text, use_real_mode);
 818         return 0;
 819 }